org.apache.hadoop.hbase.quotas

Class RateLimiter

java.lang.Object

org.apache.hadoop.hbase.quotas.RateLimiter

Direct Known Subclasses:

AverageIntervalRateLimiter, FixedIntervalRateLimiter

@InterfaceAudience.Private
 @InterfaceStability.Evolving
public abstract class RateLimiter
extends Object

Simple rate limiter. Usage Example: // At this point you have a unlimited resource limiter RateLimiter limiter = new AverageIntervalRateLimiter(); or new FixedIntervalRateLimiter(); limiter.set(10, TimeUnit.SECONDS); // set 10 resources/sec while (true) { // call canExecute before performing resource consuming operation bool canExecute = limiter.canExecute(); // If there are no available resources, wait until one is available if (!canExecute) Thread.sleep(limiter.waitInterval()); // ...execute the work and consume the resource... limiter.consume(); }

Field Summary

Fields

Modifier and Type	Field and Description
private long	avail
private long	limit
static String	QUOTA_RATE_LIMITER_CONF_KEY
private long	tunit

Constructor Summary

Constructors

Constructor and Description
RateLimiter()

Method Summary

Modifier and Type	Method and Description
boolean	canExecute() Is there at least one resource available to allow execution?
boolean	canExecute(long amount) Are there enough available resources to allow execution?
void	consume() consume one available unit.
void	consume(long amount) consume amount available units, amount could be a negative number
long	getAvailable()
long	getLimit()
abstract long	getNextRefillTime()
protected long	getTimeUnitInMillis()
(package private) abstract long	getWaitInterval(long limit, long available, long amount) Time in milliseconds to wait for before requesting to consume 'amount' resource.
boolean	isBypass()
(package private) abstract long	refill(long limit) Refill the available units w.r.t the elapsed time.
void	set(long limit, TimeUnit timeUnit) Set the RateLimiter max available resources and refill period.
abstract void	setNextRefillTime(long nextRefillTime)
String	toString()
void	update(RateLimiter other) Sets the current instance of RateLimiter to a new values.
long	waitInterval() Returns estimate of the ms required to wait before being able to provide 1 resource.
long	waitInterval(long amount) Returns estimate of the ms required to wait before being able to provide "amount" resources.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

QUOTA_RATE_LIMITER_CONF_KEY

public static final String QUOTA_RATE_LIMITER_CONF_KEY

See Also:

Constant Field Values

tunit

private long tunit

limit

private long limit

avail

private long avail

Constructor Detail

RateLimiter

public RateLimiter()

Method Detail

refill

abstract long refill(long limit)

Refill the available units w.r.t the elapsed time.

Parameters:

limit - Maximum available resource units that can be refilled to.

Returns:

how many resource units may be refilled ?

getWaitInterval

abstract long getWaitInterval(long limit,
                              long available,
                              long amount)

Time in milliseconds to wait for before requesting to consume 'amount' resource.

Parameters:

limit - Maximum available resource units that can be refilled to.

available - Currently available resource units

amount - Resources for which time interval to calculate for

Returns:

estimate of the ms required to wait before being able to provide 'amount' resources.

set

public void set(long limit,
                TimeUnit timeUnit)

Set the RateLimiter max available resources and refill period.

Parameters:

limit - The max value available resource units can be refilled to.

timeUnit - Timeunit factor for translating to ms.

toString

public String toString()

Overrides:

toString in class Object

update

public void update(RateLimiter other)

Sets the current instance of RateLimiter to a new values. if current limit is smaller than the new limit, bump up the available resources. Otherwise allow clients to use up the previously available resources.

isBypass

public boolean isBypass()

getLimit

public long getLimit()

getAvailable

public long getAvailable()

getTimeUnitInMillis

protected long getTimeUnitInMillis()

canExecute

public boolean canExecute()

Is there at least one resource available to allow execution?

Returns:

true if there is at least one resource available, otherwise false

canExecute

public boolean canExecute(long amount)

Are there enough available resources to allow execution?

Parameters:

amount - the number of required resources, a non-negative number

Returns:

true if there are enough available resources, otherwise false

consume

public void consume()

consume one available unit.

consume

public void consume(long amount)

consume amount available units, amount could be a negative number

Parameters:

amount - the number of units to consume

waitInterval

public long waitInterval()

Returns estimate of the ms required to wait before being able to provide 1 resource.

waitInterval

public long waitInterval(long amount)

Returns estimate of the ms required to wait before being able to provide "amount" resources.

setNextRefillTime

public abstract void setNextRefillTime(long nextRefillTime)

getNextRefillTime

public abstract long getNextRefillTime()